CO hydrogenation on Ru/Al/sub 2/O/sub 3/: selectivity under transient conditions

Journal Article · Mon Jun 01 04:00:00 EDT 1987 · J. Catal.; (United States)

OSTI ID:5288587

Zhou, X; Gulari, E

Transient response and isotopic tracer techniques were used to investigate the surface coverages of the reactants and the selectivity of ruthenium/alumina catalysts in CO hydrogenation. Two forms of carbon - active carbidic carbon, ..cap alpha..C/, and hydrogen-containing alkylic carbon, ..beta..C - are found to be present on the catalyst surface. Approximately 0.1 monolayer of ..cap alpha..C/ is deposited on the catalyst through the dissociative chemisorption of CO. ..beta..C is formed only in the presence of hydrogen. Unlike ..cap alpha..C/, the amount of ..beta..C on the catalyst surface is found to increase continuously. Under varying partial pressures of CO and H/sub 2/ the surface coverage of ..cap alpha..C/ changes much less than the overall rate of reaction. In addition to ..cap alpha..C/ and ..beta..C, the catalyst surface also contained approximately 0.7 monolayer of CO and 0.1 to 0.2 monolayer of inactive carbon. Measurements of product distributions of ..cap alpha..C/ and ..beta..C during the hydrogen titration transients show that for ..cap alpha..C the Schultz-Flory distribution is obeyed. In contrast, ..beta..C products do not follow the same distribution. The relative selectivities of the two species of carbon during hydrogen titration transients were very different. ..beta..C titration produced normal and branched alkanes in comparable amounts. No alkene is produced from ..beta..C. ..cap alpha..C/ titration produced primarily normal alkenes and alkanes. The results also show that the chain propagation step is much faster than the other steps in hydrocarbon synthesis (Fischer-Tropsch synthesis) and that CO dissociation is not the rate-limiting step. 21 references.

• Research Organization: Univ. of Michigan, Ann Arbor
• OSTI ID: 5288587
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 105:2; ISSN JCTLA
• Country of Publication: United States
• Language: English

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01 COAL, LIGNITE, AND PEAT
010408* -- Coal
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ALKANES
ALKENES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBIDES
CARBON
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
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CHALCOGENIDES
CHEMICAL REACTION KINETICS
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DISSOCIATION
ELEMENTS
FISCHER-TROPSCH SYNTHESIS
HYDROCARBONS
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ISOTOPE APPLICATIONS
KINETICS
LAYERS
METALS
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ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REACTION INTERMEDIATES
REACTION KINETICS
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TRACER TECHNIQUES
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